Papers by Keyword: Adiabatic Compressibility

Abstract: The consequential use of biodiesel as a source of renewable energy sustained a rapid growth over the past few years due to its major advantages like biodegradability, higher lubricity, low toxicity and low CO₂ emissions. Generally, transesterification is used for the production of biodiesel by employing base catalysis. Here, this Biodiesel is prepared from Annona Squamosa (Custard apple) seed oil with methanol by using potassium hydroxide as a catalyst which is further tested in Compression Ignition (C.I) engines. In the present study, an attempt has been made to analyze the acoustical studies on various blend compositions of Biodiesel with conventional diesel in the ratios 0%, 20%, 40%, 60%, 80% and 100% by determining relative viscosity, ultrasonic velocity and density at 303K. From these experimental data, various molecular interaction parameters like adiabatic compressibility, viscous relaxation time, inter molecular free length, specific acoustical impedance are calculated and the results are discussed in the light of solute-solvent interaction.

Abstract: The present experimental investigation was carried out in order to explore the possible molecular interactions of D(+) mannose with mixed solvent of aqueous NaCl, KCl , MgCl₂ and CaCl₂at 303 K. Experimental values of densities and ultrasonic velocities were carried out of the ternary mixture solution D(+) mannose with aqueous NaCl ,KCl, MgCl₂ and CaCl₂. Aqueous alkali metal halides (NaCl ,KCl , MgCl₂ and CaCl₂ ) were added under different molalities with D(+) mannose. The related and relevant parameters correlated to the present study such as adiabatic compressibility K_s, acoustic impedance Z, apparent molal volume ф_v, apparent molal adiabatic compressibility, ф_Ks, and partial molal volume ф⁰_v and partial molal adiabatic compressibility, ф^o_Ks at infinite dilution. The present investigation has exploited the possible molecular associations such as ion-ion, ion-solvent, solute-solute and solute-solvent interactions in these systems. It has been observed that there exist strong solute-solvent interaction and complex formation between in these ternary systems.

Abstract: Rheology and ultrasonic velocity (at 2 MHz frequency) properties of Ethylene glycol (EG)-water mixed nano-coolants are studied at different temperatures. Variation in density and viscosity is found to be non-linear with increasing EG concentration. The viscosity of the mix system varies from 3.5 to 16.9 mPa.s. The results show that with increasing EG concentration in the system the ultrasonic velocity increases, reaches maximum and then decreases. The similar trend is observed for all the temperature under investigation. From these data, the adiabatic compressibility, mean free path and attenuation co-efficient have been calculated. The observed variation is explained considering the relative strength of hydrogen bond between EG and water.

Abstract: Ultrasonic velocity measurements are carried out on four nOm compounds viz., N-(p-n-methoxy and ethoxy benzylidene)-p-n-dodecyl and tetradecyl anilines, 1O.12, 1O.14, 2O.12 and 2O.14. The first three compounds exhibit mono variant nematic phase while the last compound exhibits nematic and smectic-A phases with variable thermal ranges. The temperature dependence of sound velocity, U shows minima at the isotropic-nematic and nematic-smectic-A transitions. In conjunction with the density data of these compounds, the thermo acoustic parameters such as adiabatic compressibility (β_ad), the molar sound velocity (Rao’s number) (R_n), molar compressibility (W), molecular free length (L_f) and available volume (V_a) are estimated. In addition the intermolecular free length (L_f) is estimated in three different ways employing density and ultrasonic velocity data. The results are compared with the data available in literature of other compounds.

Abstract: In the present work, ultrasonic velocity measurements have been carried out in solutions of silver nanoparticles in the polymer matrix of poly(sodium, 4-styrene sulphonate) using Sing-Around technique, operated at 2 MHz.. The ultrasonic velocity of propagation shows an abnormal behaviour, indicating the existence of the phase separations in nano-colloidal solution. The effect of polymer is observed to be predominant in the phase separation at the lower concentrations of polymer in the mixture. At higher concentrations of the polymer in the mixture the phase separation seems to subside at higher temperature.

Abstract: Nanoparticles exhibit unusual properties in contrast with their bulk properties due to small particle size and quantum confinement. In the present work, ultrasonic velocity and density measurements have been carried out in solutions of silver nanoparticles in micellar dispersion of cetyl tri-metyl ammonium bromide, CTAB. Ultrasonic velocity measurements at different concentrations of surfactant and temperatures were carried out using Sing-Around technique, operated at 2MHz. It is observed that ultrasonic velocity and adiabatic compressibility show abnormal behaviour with increase in concentration of CTAB in the solution, indicating the existence of the phase separations in nano-colloidal solution.